table thead th {
    text-align: left;
    color: #fff;
    background-color: #000;
}

/*选取小于等于3的标签，即前三格表格体*/
table tbody tr:nth-child(-n+3) {
    color: red;
}

table tbody tr:nth-child(even) {
    background-color: #bbb;
}

input {
    margin: 20px;
    width: 100px;
    border: 2px solid #ddd;
    transition: border-color, width .5s;
}

input:focus {
    width: 200px;
    border-color: cornflowerblue;
}

.banner {
    position: relative;
    overflow: hidden;
    width: 250px;
    height: 150px;
    background-color: red;
}

.banner ul {
    margin: 0;
    padding: 0;
}

.banner li {
    display: block;
}

.sliders {
    position: absolute;
    right: 0;
    left: 0;
    width: 100%;
    height: 100%;
    animation: .5s slider-init linear;
}

.sliders li {
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    color: #fff;
    animation: .5s slider-out linear;
}

#slider-1 {
    background-color: red;
}

#slider-2 {
    background-color: green;
}

#slider-3 {
    background-color: blue;
}

.sliders li:target {
    left: 0%;
    animation: .5s slider-in linear;
}

@keyframes slider-init {
    0% {
        left: -100%
    }
    100% {
        left: 0%;
    }
}

@keyframes slider-out {
    0% {
        left: 0%;
    }
    100% {
        left: -100%;
    }
}

@keyframes slider-in {
    0% {
        left: 100%;
    }
    100% {
        left: 0%;
    }
}

.btn {
    position: absolute;
    right: 0;
    bottom: 0;
    display: flex;
    z-index: 100;
}

.btn a {
    display: block;
    margin: 0 1px;
    padding: 10px 14px;
    text-decoration: none;
    color: white;
    background-color: rgba(255, 255, 255, .5);
}

